294 Bower . — Studies in the Phytogeny of the Filicales . 
the creeping habit of the Gleicheniaceae and the upright dendroid types of 
the Cyatheaceae. 
In this connexion it may be noted that terminal branching occasion- 
ally is seen in the dendroid Cyatheaceae. An example of this is shown in 
PL XXXII, Fig. M, in a plant in the Glasgow Botanic Garden. Here there 
is an apparent dichotomy, the two resulting branches having continued their 
development equally. Anatomical examination would be necessary to 
prove that the branching was really dichotomous in this case, and naturally 
that cannot be undertaken. So it must suffice for the present to state that 
all the external indications are favourable to the branching having been 
a true dichotomy. If this were really the case, it would be a further point 
in common with the Gleicheniaceae, in which it has been shown that 
dichotomy is frequent. 
2. As regards the form of the leaf the Gleicheniaceae and Cyatheaceae 
seem at first sight widely divergent, and Lophosoria does not appear to help 
any transition. But if a comparison be made between the ultimate pinnules 
of Lophosoria (PI. XXXI, Fig. H) and those of some species of Gleichenia 
(PI. XXX, Figs. C and E) a similarity of outline, of venation, and even of tex- 
ture is apparent ; the soral similarity is, however, the most important feature 
of all. The divergence is then in the general habit of the leaf rather than in 
the details. But even in general habit there are features which link the two 
families together. The most marked characteristic of the leaf of Gleichenia 
is its apical growth, which may be continued indefinitely though interrupted 
at seasonal intervals. Looked at broadly, however, the leaf is constructed 
upon the ordinary pinnate type, and its peculiarities depend upon irregu- 
larities in time and extent of the intercalary growth of the rachis, and 
of the branches of higher order. For the most part the intercalary growth 
between the pairs of pinnae is strong, so that they are far apart, and usually 
uniformly removed from one another. In the Cyatheaceae it is less strong, 
and the pinnae are more closely aggregated. But as a rule the pinnae 
stop short at some distance from the base of the mature leaf, intercalary 
growth having been strongest below the lowest pinnae. A special interest, 
however, for comparative purposes lies in those cases where this rule is not 
maintained, with the result that basal pinnae are left behind at the base of 
the leaf, the intercalation of the petiole having taken place above them. 
These basal pinnae have long been known as the so-called ‘ aphlebiae and 
the example commonly quoted is that of Hemitelia capensis. But as 
a matter of fact it is a feature which exists sporadically in all the three 
genera of the Cyatheaceae. PI. XXXIII, Fig. N shows a very pronounced 
example of Hemitelia setosa , Mett., from the Edinburgh Botanic Garden. 
Fig. O shows the case of an Alsophila from Jamaica, growing in the Glasgow 
Botanic Garden ; and Christ has figured a very marked case of basal pinnae 
in a species of Cyathea (‘ Geographie der Fame’, Fig. 24). It thus appears 
